1. Field of the Invention
The present invention relates to a computer controlled cleaning tool. More specifically, the present invention relates to a cleaning tool for automatically cleaning a preheater rotor used in electrical power plants.
2. Description of the Related Art
Using high pressure water which is forced through a preheater rotor is well known. Typically, after prolonged use the preheater rotor or rotors of an electrical power plant become coated and clogged with debris such as coal ash. This occurs when hot gases from a plant's combustion process are routed to a preheater rotor, which transfers heat to fresh air routed back to the combustion process to increase the burning efficiency. When the rotors become coated with debris the heat transferring efficiency is reduced and therefore the rotors need to be cleaned periodically.
Typically the preheater rotors are up to twenty feet in diameter and a high pressure water stream of approximately 0.25 inches is applied to the rotor. It can easily be seen that this cleaning process takes a long time, anywhere from 25 to 50 hours depending on the width of the water stream and the rate at which the rotor is rotated past the stream.
There have been attempts made in the past to increase the efficiency and ease of this cleaning. One such attempt includes using programmable logic control (PLC) to move a high pressure water nozzle along a bar extending radially from a hub of the rotor.
This system required an operator to compute how long it would take a rotor to make a complete revolution based on a rotor rotation rate which the operator would independently set. The operator would then compute how long the cleaning would take based on how much of the rotor was to be cleaned and the width of the water nozzle spray. All of the computed parameters would then be entered into the PLC which would then set a timer and move the spray nozzle by an amount equal to the nozzle spray width when the timer indicated the rotor had completed a revolution.
It is therefore desirable to provide a system which would enable only basic direct information, such as inner and outer radii of the rotor, spray width, and the rotor rotation rate or the time to complete the cleaning to be entered and have the cleaning tool automatically clean the area of the rotor bounded by the inner and outer radii.